001/*
002 * Licensed to the Apache Software Foundation (ASF) under one
003 * or more contributor license agreements.  See the NOTICE file
004 * distributed with this work for additional information
005 * regarding copyright ownership.  The ASF licenses this file
006 * to you under the Apache License, Version 2.0 (the
007 * "License"); you may not use this file except in compliance
008 * with the License.  You may obtain a copy of the License at
009 *
010 *   https://www.apache.org/licenses/LICENSE-2.0
011 *
012 * Unless required by applicable law or agreed to in writing,
013 * software distributed under the License is distributed on an
014 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
015 * KIND, either express or implied.  See the License for the
016 * specific language governing permissions and limitations
017 * under the License.
018 */
019package org.apache.bcel.classfile;
020
021import java.io.DataInput;
022import java.io.DataOutputStream;
023import java.io.IOException;
024
025import org.apache.bcel.Const;
026
027/**
028 * This class is derived from the abstract {@link Constant} and represents a reference to a module.
029 *
030 * <p>
031 * Note: Early access Java 9 support- currently subject to change
032 * </p>
033 *
034 * @see Constant
035 * @since 6.1
036 */
037public final class ConstantModule extends Constant implements ConstantObject {
038
039    private int nameIndex;
040
041    /**
042     * Initialize from another object.
043     *
044     * @param c Source to copy.
045     */
046    public ConstantModule(final ConstantModule c) {
047        this(c.getNameIndex());
048    }
049
050    /**
051     * Initialize instance from file data.
052     *
053     * @param file Input stream.
054     * @throws IOException if an I/O error occurs.
055     */
056    ConstantModule(final DataInput file) throws IOException {
057        this(file.readUnsignedShort());
058    }
059
060    /**
061     * Constructs a ConstantModule.
062     *
063     * @param nameIndex Name index in constant pool. Should refer to a ConstantUtf8.
064     */
065    public ConstantModule(final int nameIndex) {
066        super(Const.CONSTANT_Module);
067        this.nameIndex = nameIndex;
068    }
069
070    /**
071     * Called by objects that are traversing the nodes of the tree implicitly defined by the contents of a Java class. I.e.,
072     * the hierarchy of methods, fields, attributes, etc. spawns a tree of objects.
073     *
074     * @param v Visitor object.
075     */
076    @Override
077    public void accept(final Visitor v) {
078        v.visitConstantModule(this);
079    }
080
081    /**
082     * Dumps constant module to file stream in binary format.
083     *
084     * @param file Output file stream.
085     * @throws IOException if an I/O error occurs.
086     */
087    @Override
088    public void dump(final DataOutputStream file) throws IOException {
089        file.writeByte(super.getTag());
090        file.writeShort(nameIndex);
091    }
092
093    /**
094     * Gets the dereferenced string.
095     *
096     * @param cp the constant pool.
097     * @return dereferenced string.
098     */
099    public String getBytes(final ConstantPool cp) {
100        return (String) getConstantValue(cp);
101    }
102
103    /**
104     * Gets the String object.
105     *
106     * @param cp the constant pool.
107     * @return String object.
108     */
109    @Override
110    public Object getConstantValue(final ConstantPool cp) {
111        return cp.getConstantUtf8(nameIndex).getBytes();
112    }
113
114    /**
115     * Gets the name index in constant pool of module name.
116     *
117     * @return Name index in constant pool of module name.
118     */
119    public int getNameIndex() {
120        return nameIndex;
121    }
122
123    /**
124     * Sets the name index in the constant pool.
125     *
126     * @param nameIndex the name index in the constant pool of this Constant Module.
127     */
128    public void setNameIndex(final int nameIndex) {
129        this.nameIndex = nameIndex;
130    }
131
132    /**
133     * @return String representation.
134     */
135    @Override
136    public String toString() {
137        return super.toString() + "(nameIndex = " + nameIndex + ")";
138    }
139}